The Ex Ante process estimates the potential energy savings for an energy efficient measure before it is installed based on predictions of typical operating conditions and baseline usage. The process is the basis for utilities to claim savings for their energy efficiency portfolios. The Ex Ante process covers deemed measures (DEER and non-DEER), measures that have well-known and consistent performance characteristics, and custom measures.

The Database of Energy Efficient Resources and Ex Ante Regulatory Support RFP No. 12 PS 5125 contains details on the scope of work for the four work areas of Ex Ante Review.

Rulemaking R.13-11-005 - Establishes a proceeding in which to fund the current energy efficiency portfolios through 2015, implement energy efficiency "rolling portfolios", and address various related policy; Phase I Decision - October 27, 2014; Compliance Filing Corrections from Decision - November 11, 2014

Ex Ante Review Fact Sheets

The set of fact sheets provide high level information and policy background to the Ex Ante review process. The purpose is to provide the public and stakeholders a better understanding of how the PUC conducts its review process.

Ex Ante Review Fact Sheet #1 provides information on how cost effectiveness is estimated.

Ex Ante Review Fact Sheet #2 provides information on different components of the review process and how each of them works.

Ex Ante Review Fact Sheet #3 provides information on high-level assumption for HVAC savings estimates currently used for the review process.

Energy Modeling Tools Workshop Materials

On September 18, 2015, from 9:30am to 4:30pm, Commission staff is holding a workshop to exchange information on the predominant whole building energy modeling simulation tools in the market to understand what’s out there, how it’s used, and how we understand the strengths and weaknesses of each tool.


DEER (Database for Energy Efficient Resources)

DEER, the Database for Energy Efficient Resources, provides energy savings estimates for typical energy efficient technologies and measures. The database contains information and data, such as unit energy savings, effective useful life values, and net to gross ratios for measures that are commonly installed in the marketplace. DEER is currently managed by the Energy Division, with funding provided by California ratepayers. The DEER website,, contains the database and all supporting documentation. Data can be accessed and downloaded through the database interface Remote Ex Ante Database Interface (READI) on the DEER website.

Instructions for analyzing measure savings impacts and parameters can be found in this document.

The DEER Master Documentation compiles DEER2008, DEER2011, and DEER2014 update documents and data into one directory. The Excel spreadsheet contains information and links to the individual documents. Please follow these steps to ensure the links work: (1) Extract the main folder onto your desktop and (2) Enable editing and macros in the excel file.

The DEER Update Plan outlines the process for updates for the 2014 and beyond cycles.


D.05-01-055 directed the Energy Division to provide oversight of research and analysis of the energy efficiency values. The Commission placed the updates to DEER under the management of regulatory staff.

In D.05-04-051, the Commission determined that DEER shall be the source of assumptions used to estimate load impacts to the extent possible. 

D.12-05-015 adopted the DEER2011 release for use in planning the 2013-14 energy efficiency program cycle. In R.09-11-014, the Commission also determined that the codes and standards that will become effective in 2014 should be used to update the baseline values during the 2013-14 energy efficiency program cycle. 

Upcoming and Current Events

DEER Updates

For more information, contact Peter Biermayer at

Non-DEER Workpaper Values for Energy Efficiency Measures

Program administrators and implementers develop non-DEER workpapers for measures that are not captured in DEER. Potential energy savings estimates are calculated based on best available information and extrapolation from DEER values or methods, as appropriate. Program administrators submit workpapers to the Energy Division for review on specific non-DEER measures. The Energy Division reviews a sub-selection of the submissions and releases dispositions with adjusted values, if needed.  

Workpaper Development Training and Frequently Asked Questions (FAQs)


Development, review and approval of non-DEER workpapers has evolved through several decisions. D.09-09-047 gave Energy Division authority to review and approve non-DEER workpapers and required Energy Division to develop a process for submittal, review and freezing of non-DEER measures.  During the 2010-2012 program cycle, an administrative law judge ruling dated 11/18/2009 in A.08-07-021 provided a standardized review and approval process for Phase 2 non-DEER workpapers including:

  • Requirements for utilizing DEER values and methods in the development of non-DEER measures.
  • A timeline for workpaper review that required Commission staff to perform a preliminary review for additional information within 15 days and the final review within 25 days of receiving the additional review.
  • A requirement for consideration of the latest evaluation, measurement and verification published studies in the development of ex ante values including energy impacts, cost data, effective useful life, remaining useful life, and net-to-gross ratios.
  • Provision for retrospective staff reviews of frozen and workpapers not reviewed if the measures covered by a workpaper eventually become high-impact measures, measures with the largest amount of energy savings claimed by investor-owned utilities.
  • D.10-04-029 approved Application 08-07-021 and required investor-owned utilities to cooperate with energy division to allow upfront consultation regarding workpapers.  D.11-07-030 approved all of Application 08-07-021 in regards to Phase 2 review, except the provision for retrospective staff review, which was then removed.

D.12-05-015 is the guidance decision covering 2013-2014 energy efficiency applications and includes a process for workpaper review that builds upon the process established in the previous decisions. D.12-05-015 included the following requirements:

  • Ex ante values shall be updated in consideration of 2006-2008 evaluation results.
  • Utilities shall include workpapers in their initial 2013-2014 applications for all measures that are not specifically included in the DEER database.  (NOTE: Staff and utilities refer to workpapers submitted with the initial 2013-2014 applications as “Phase 1” workpapers.)
  • Update and review of workpapers shall be given to High Impact Measures.
  • If Staff is unable to review all workpapers submitted with the initial 2013-2014 workpapers, the un-reviewed workpapers shall receive “interim approval,” and Staff may review any of these in the future, with revisions applied prospectively.
  • A mid-cycle review is included that prescribes a process for reviewing any workpapers that have interim approval as well as any Phase 2 workpapers that are submitted during the cycle.
  • New non-DEER measures may be added during the program cycle. Staff may assign new non-DEER measures “interim approval” prior to the completion of any necessary research.
  • A Phase 2 submission and review process is included that limits the time for staff review of workpapers and does not allow the use of the disposition of “conditional approval” that was previously allowed under D.11-07-030.
  • Every six months Commission Staff will develop a draft resolution covering any disputed workpapers that will be subject to a Commission vote.

Custom Measures and Projects

Custom measures and projects are site-specific energy efficiency projects. Custom projects require unique calculations for each project, as they do not rely on fixed DEER or workpaper values.  For custom measures and projects the ex ante values cannot be forecasted in advance since the preliminary ex ante values are not known until the project is identified.  Final ex ante values are not developed until the project is completed.  Commission Decision 11-07-030 establishes a clear process by which ex ante energy savings estimates from custom measures and projects are reviewed.


D.11-07-030 approves that the Energy Division custom project ex ante review process is reasonable and should be adopted. Attachment B of the filing details how the investor-owned utilities’ energy savings claims will be reviewed:

  • Under the General Review process, the Energy Division will review tools, measures, and projects, as well as inputs to the tools for selected projects. The tool reviews will be done on a prospective basis.
  • The Pre-Installation Review process allows the Energy Division to perform a parallel review process with the investor-owned utilities, and then allows for the Energy Division to provide inputs and recommendations.
  • The Post-Installation Review process is used to provide the Energy Division with opportunity to review the accuracy of energy savings claims assumed by the investor-owned utility prior to the utility making its final incentive payment to its customer.
  • Under the Investor-Owned Utility Claim Review process, the Energy Division conducts a review of energy savings for custom projects to ensure that recommendations made by Energy Division were accurately reflected in the claim.

Customer process guidance documents can be found on this page.